Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a manufacturing method of an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus, and a phthalocyanine crystal and a manufacturing method of a phthalocyanine crystal.
Description of the Related Art
Since the oscillation wavelength of a semiconductor laser commonly used as an image exposing unit in the field of electrophotography is in the long wavelength range of 650 to 820 nm, electrophotographic photosensitive members having high sensitivity to the light in the long wavelength range are currently under development.
Phthalocyanine pigments are effective as charge generating substances having high sensitivity to the light ranging to such a long wavelength region. Oxytitanium phthalocyanine and gallium phthalocyanine in particular have excellent sensitivity properties, and various crystal forms have been reported until now.
Although an electrophotographic photosensitive member using a phthalocyanine pigment has excellent sensitivity properties, a problem is that the generated photo carriers tend to remain in a photosensitive layer so as to act as a memory, easily causing potential variation such as ghosting.
Japanese Patent Application Laid-Open No. 2001-40237 discloses that the addition of a specific organic electron acceptor to a phthalocyanine pigment during acid pasting has a sensitizing effect. This method has, however, problems that an additive (organic electron acceptor) may be subject to a chemical change and that the conversion to a desired crystalline form may be difficult in some cases.
Japanese Patent Application Laid-Open No. H07-331107 discloses a hydroxygallium phthalocyanine crystal which contains a polar organic solvent. According to the description, with use of a transformation solvent such as N,N-dimethylformamide, the molecule of the transformation solvent is incorporated in the crystal, so that a crystal having excellent sensitivity properties is produced.
Various attempts have been made to improve electrophotographic photosensitive members as described above.
For further improvement in high-quality picture in recent years, it is desired to prevent image degradation due to ghosting in various environments. Japanese Patent Application Laid-Open No. H07-331107 discloses a phthalocyanine crystal which contains 2.1% by weight N,N-dimethylformamide. As a result of examination by the present inventors, it was found that the generated photo carriers are liable to remain in a photosensitive layer depending on the content of N,N-dimethylformamide, easily causing potential variation such as ghosting in some cases. It was thus found that there is a room for further improving ghosting.